Belaich A, Fierobe H P, Baty D, Busetta B, Bagnara-Tardif C, Gaudin C, Belaich J P
Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique, Marseille, France.
J Bacteriol. 1992 Jul;174(14):4677-82. doi: 10.1128/jb.174.14.4677-4682.1992.
Sequence analysis of the endoglucanase EGCCA of Clostridium cellulolyticum indicates the existence of two domains: a catalytic domain extending from residue 1 to residue 376 and a reiterated domain running from residue 390 to 450. A small deletion in the C terminal end of the catalytic domain inactivated the protein. From the analysis of the sequences of 26 endoglucanases belonging to family A, we focused on seven amino acids which were totally conserved in all the catalytic domains compared. The roles of two of these, Arg-79 and His-122, were studied and defined on the basis of the mutants obtained by introducing various substitutions. Our findings suggest that Arg-79 is involved in the structural organization of the protein; the His-122 residue seems to be more essential for catalysis. The role of His-123, which is conserved only in subfamily A4, was also investigated.
解纤维梭菌内切葡聚糖酶EGCCA的序列分析表明存在两个结构域：一个催化结构域，从第1位氨基酸延伸至第376位氨基酸；一个重复结构域，从第390位氨基酸延伸至第450位氨基酸。催化结构域C末端的一个小缺失使该蛋白失活。通过对属于A家族的26种内切葡聚糖酶序列的分析，我们聚焦于在所有比较的催化结构域中完全保守的7个氨基酸。基于通过引入各种取代获得的突变体，研究并确定了其中两个氨基酸（Arg-79和His-122）的作用。我们的研究结果表明，Arg-79参与蛋白质的结构组织；His-122残基似乎对催化更为重要。还研究了仅在A4亚家族中保守的His-123的作用。
